sinx+siny=根号3 cosx+cosy=2根号3/3 求tanxtany错了，第一个我等于根号2

解:
两条件式平方相加,得
2+2cos(x-y)=13/3
→cos(x-y)=7/6矛盾了题目有问题sinx+siny=根号3要改为根号2 解:
两条件式平方相加,得
2+2cos(x-y)=10/3
→cos(x-y)=2/3 …… (1)
两条件式平方相减,得
cos2x+cos2y+2cos(x+y)=-2/3
→2cos(x+y)cos(x-y)+2cos(x+y)=-2/3
代(1)代入,得
4/3*cos(x+y)+2cos(x+y)=-2/3
→cos(x+y)=-1/5 …… (2)
(1)+(2),得2cosxcosy=7/15 …… (3)
(1)-(2),得2sinxsiny=13/15 …… (4)
(4)÷(3),得tanxtany=13/7.

sinx+siny=根号2 (1)cosx+cosy=2根号3/3 (2)(1)平方+(2)平方2+2sinxsiny+2cosxcosy=2+4/3cosxcosy+sinxsiny=2/3 (3)cos (x-y)=2/3 (4)(2)平方-(1)平方cos2x+cos2y+2(cosxcosy-sinxsiny)=-2/32cos(x+y)cos(x-y)+2cos(...